One of the potential problems with oxytocin use during delivery is that it loses its effectiveness if the uterus has previously been pre-exposed to its high doses and/or for a prolonged duration during labor. This phenomenon is termed OTR desensitization, and can result in the attenuation of myometrial contractility induced by subsequent oxytocin administration, as well as PPH due to poor uterine tone. Furthermore, oxytocin can produce potentially fatal maternal hemodynamic adverse effects when administered at high doses, so it is advantageous to be able to use as low a dose as possible to obtain good uterine muscle tone.